Well logging tool



Dec. 5, 1967 R. A. ANDERSON WELL LOGGING TOOL 4 Sheets-Sheet 1 INVEN'IOR. Reva/a /4. finds/Jan Filed June 215, 1965 ATTORNEY 4 Sheets-Sheet 2 Filed June 23, 1965 INVENTOR.

BY M

,4 fro/WW5 Dec. 5, 1967 Filed June 215,

R. A. ANDERSON WELL LOGG I NG TOOL 4 Sheets-Sheet 3 Rana/a A. AHO/QIJON ATTORNEY Dec. 5, 1967 R. A. ANDERSON WELL LOGGING TOOL 4 Sheets-Sheet 4 Filed June 23, 1965 /?0/7a /a/ 4. flflc/exuon INVIZN'I'OR.

ATTORNEY United States Patent 3,356,146 WELL LOGGING TOOL Ronald A. Anderson, Houston, Tex., assignor, by mesne assignments, to Schlumberger Technology Corporation, Houston, Tex., a corporation of Texas Filed June 23, 1965, Ser. No. 466,305 19 Claims. (Cl. 166-241) ABSTRACT OF THE DISCLOSURE As one embodiment of the present invention disclosed herein, a well tool is provided with a linkage system for movably supporting another and separate portion of the tool so that this separate portion can be urged against a well bore wall without imposing substantial lateral reaction forces on the first portion of the tool. A hydraulic system is further provided for selective control of the linkage system.

This invention relates to logging apparatus for well bores and, more particularly, logging apparatus wherein a relatively short, heavy skid housing containing the logging apparatus is arranged to be suspended from a main housing and maintenance in substantially constant contact relationship with the wall of the well bore independently of such main housing.

Heretofore, most logging apparatus has been mounted in an elongated tool housing, together with the necessary circuitry arrangements and urged against the wall of a well bore by bow springs. Because the housing is quite heavy, it gravitates to the lower side of the well bore and slides therealong. Obviously, where the well bore has sections of varying diameters such as wash-outs, caves and the like, an elongated tool tends to bridge over such sections, therefore, sections of the tool are separated from the wall of the well bore. In tools such as a wet logging device, wherein contact of the device with the well bore is essential for accuracy, it will be appreciated that such separations tend to give rise to some inaccuracy in the measurements. In developing an apparatus to overcome the shortcomings of prior logging devices, it is necessary to as great an extent as possible, to minimize the weight and length of the logging device.

Other types of well logging apparatus employ relatively small and light-weight pads carrying electrodes which are urged into contact with the wall of the Well bore by bow springs or linkage attached to an elongated main housing. In this type of apparatus, the housing may be slid along the lower side of the well bore with a pad extended by linkage to the upper side of the well bore or two or more pads may be arranged to extend relative to the tool housing into contact with the well bore.

Accordingly, it is an object of the present invention to provide a new and improved well tool having a relatively short, lightweight main support housing and a wallengaging member which is adapted to be maintained in a substantially constant contact relationship with the wall of a well bore independently of the main support housing.

It is another object of the present invention to provide new and improved apparatus including a relatively short, lightweight main housing, and suspended therefrom, a logging device contained in a relatively short, skid housing which is adapted to be maintained in a substantially constant contact relationship with the wall of a well bore and decoupled from movement forces between the main housing and skid housing.

A further object of the present invention is to provide a new and improved Well logging apparatus having a linkage system for maintaining a relatively short skid housing with a prescribed face in a substantially constant contact relationship with the wall of the Well bore with sufiicient 3,356,146 Patented Dec. 5, 1967 force to assure intimate contact with the wall of the borehole.

A still further object of the present invention is to provide a new and improved well logging apparatus and hydraulic system for controlling the operation of the logging apparatus.

Yet still another object of the present invention is to provide a new and improved well tool having at least two relatively short skid housings pivotally suspended in tandem from a main support housing and a common hydraulic system for manipulating the skid housings between wallengaging and retracted positions.

In the present invention, a relatively short, skid housing is suspended by a pivotally coupled support link member from a main housing. A logging device such as a source and detector of radioactivity is contained within the skid housing. An eccentering or caliper arm is linked to the skid housing for relative movement to the skid housing so that the caliper arm and skid housing can be urged into contact with the wall of the well bore. A linkage system is provided for the caliper arm and skid housing for developing the relative movement therebetween without the transmission of undesirable moments or forces to the main housing. The linkage system is powered by an actuating spring and hydraulic means which are carried on the pivotally coupled support link and which are responsive to a hydraulic system in the main housing.

FIGS. 1 and 2 illustrate apparatus embodying the present invention showing the wall-engaging member and skid housing in extended and retracted positions in a well bore;

FIG. 3 is a perspective view of part of the linkage system embodied in the present invention;

FIGS. 4 and 5 are schematic diagrams of the hydraulic system and actuating mechanism of the present invention in two different conditions of operation;

FIG. 6 is a detailed view of the pivotal connection between the main tool housing and the pivotally coupled link portion of the tool;

FIG. 7 is a detailed sectional view of a piston assembly in the actuating mechanism;

FIG. 8 illustrates another embodiment of the present invention comprising a tandem arrangement of well-logging tools suspended from a main housing; and

FIG. 9 is a detailed view of an alternative actuating mechanism.

Referring now to FIGS. 1 and 2, apparatus embodying the present invention includes an elongated, cylindrical main housing assembly 12, which has, at its lower end, a tubular member or chassis 14 which is open on opposed sides and terminated with a bottom nose piece 16. The nose piece 16 and chassis 14 form a generally protective cover for an exploratory apparatus or logging device 18 such as a radioactivity device, which apparatus is mounted in a skid housing 19. Skid housing 19 is solely suspended from the main housing 12 by means of a pivotally connected support link member 20.

A wall-engaging shoe 22 and eccentering or calipering arm 24 are pivotally connected to the skid housing 19 so that, in normal operation, the shoe 22 contacts one side of the well bore intermediate of the length of the prescribed face of the skid housing 19 while the face of the skid housing 19 is maintained in contact with the opposite side of the well bore as shown in FIG. 1. A pin 23 extends from the lower end of the skid housing 19 to engage a lower wall 25 of the tubular member 14 and thereby limits the extension of the skid housing relative to the chassis 14. The chassis 14 has elongated windowlike openings 26 and 28 sized to permit both the shoe 22 and skid housing 19 respectively to be retracted to a position within the general cylindrical confines of the chassis 14. Thus, it will be appreciated that retraction of the shoe 22 and skid housing 19 into the tubular member 14 facilitates passage of the entire assembly into an empty or fluid filled well bore 30, the assembly being transported by means of a cable 32 and winch (not shown) in the customary manner.

The skid housing 19, is arranged with respect to the link member 20 and the back-up shoe 22 so that when urged into contact with the wall of well bore 38, the exploratory apparatus 18 follows very closely along the contours of the well bore as the contours vary. Referring more particularly to FIG. 3, the relationship of linkages with the link member 20 and back-up shoe 22 will become more apparent. Support link member 20 has its lower end pivotally connected by pins or the like at pivot point 34 to support members 33 extending from the upper end of skid housing 19. The skid housing 19 is also pivotally connected by means of a brace 35 to an intermediate point on the calipering arm 24 at pivot point 36. The calipering arm 24 is formed in the shape of a bell crank, having a short arm 24a connected to a link member 38 at pivot point 40. The remaining long arm 24b of the bell crank has a pivot pin 41 at its end, which pin is slidably received in elongated slots 42 in the shoe 22. A link member 43 is pivotally connected between the long crank arm 24b and the upper end of shoe 22. Link member 43 guides and pulls on the shoe 22 as the shoe pivots about the end of crank arm 24b so that the flat face of the shoe 22 is free to follow the contour of the borehole as the arm 24 is pivoted about pivot point 36 relative to the skid housing 19. Thus, the face of the shoe 22 and the face of the skid housing 19 are movable relative to one another to remain in intimate contact with the sidewalls of a varying well bore.

The end of the short crank arm 24a is pivotally connected to the link member 38 which in turn is connected to one end of a piston rod 44 by a pin 45 while the other end of the rod 44 terminates at a piston 46 (FIGS. 4 and slidably received within a hydraulic cylinder 48. The cylinder 48 is formed as a part of the support link member 20 which is pivotally connected between the skid housing 19 and main housing 12. The upper end of the support link member 20 is connected to the chassis 14 by means of a pair of trunnions 50 forming a single pivot point between the main housing 12 and all portions of the apparatus which are suspended from the support link member 20. The lower end of the support link member 20 is connected to the skid housing 12 by pins at pivot point 34.

Referring now to FIG. 6, the means for pivotally connecting the support link member 20 to the main housing 12 is shown in detail. The pair of trunnions 50 are welded onto the sidewall of the chassis portion 14 of the main housing 12 and extend inwardly therefrom. J slots 51 are formed on opposite sides of the upper end of the support link member 20. In order to connect the link member to the chassis 14, the link member 20 is placed at an angle with respect to the chassis 14 so that the outer end 53 of the long portion of the J slots are aligned with the trunnions 50. The link member 20 is then raised upwardly and moved outwardly away from chassis 14 whereupon the trunnions 50 are moved into the short portion of the J slots. The link member 20 is then rotated downwardly, pivoting on the trunnions 50. A plug 55 of Teflon, rubber or the like is then inserted into each of the long portions of the slots 51 to prevent the trunnions 50 from sliding in the slot. The contour of the plugs 55 is such that the forces applied by the trunnions 50 to the plugs 55 tend to hold the plugs in place in the J slot. This arrangement of pins and J slots for providing the pivotal connection between housing 12 and link member 20 permits easy removal of the link member 20 from the tool assembly for repair of parts on the member 20. Such removal of the member 20 is accomplished by disconnecting the pin and J-slot connection described above and removing pins at 34 and 45 to free the lower end of link member 20.

From the foregoing, it will be appreciated that the upper end of cylinder 48, mounted on link member 20, is held in place by the main pivot connection 50. The lower end of the cylinder is connected to the skid housing. The piston rod in turn is connected at its lower end to one end of the bell crank 24 through the link 38. The bell crank or eccentering arm 24 is pivotally connected intermediate its ends to the skid housing at pivot point 36.

A pair of flexible conduits extend from ports above and below the piston 46 in the cylinder 48 to a hydraulic fluid system in the main housing 12. This system will be described hereinafter in more detail with reference to FIGS. 4 and 5. The exploratory apparatus or tool may, for example, be comprised of a detector cartridge such as a scintillation device and a radioactive source. Except for the space for the detector and source the skid housing 19 would normally be filled with heavy shielding material such as lead. A wear resistant surface such as tungsten carbide would be mounted on the skid housing 19 to prevent the tool from wearing where it contacts the well bore.

Referring now to the schematic drawings of FIGS. 4 and 5, a hydraulic system is provided for actuating the power means which is shown as being a hydraulic cylinder 48 and piston 46. The intermediate portion of the main housing 12 is closed off by upper and lower walls to form a fluid reservoir 61 which contains oil or other suitable fluid. The upper wall is formed by a plug member 62 having a sealing ring 63 and secured in the upper portion of housing 12. The lower wall of the fluid reservoir is provided by a flexible gas proof metal bellows 64 which serves to pressure balance the hydraulic system and allow for expansion of oil in the reservoir. Well fluid in the well bore, if present, is admitted through openings 26 and 28 in chassis 14 to act on one side of the bellows, while the other side of the bellows is in fluid communication with the reservoir 61. Hence, the pressure in the reservoir is balanced with respect to hydrostatic pressure of the Well fluid on the exterior of the tool housing.

Within the reservoir 61 is a hydraulic system which includes a hydraulic power section, a control valve assembly and a hydraulic control section for operating the cylinder and piston mounted on the support link member 20.

Included in the power section are a pump 66 and an electric motor 68. The hydraulic control section consists of a relief valve 79, a check valve 71, and a solenoid operated valve 72, operated by solenoid 74. The pump has an inlet conduit (not shown) opened to the oil reservoir in the housing and an outlet line or conduit 76 coupled by a conduit 77 to the relief valve 70. The relief valve 70 includes a valve portion (not shown) arranged to couple the conduit 77 to a reservoir outlet in valve 70 whenever a predetermined maximum pressure in pump outlet line 76 is reached. The outlet line 76 is further coupled to the check valve 71. The other side of the check valve is coup-led by a conduit 78 to the control valve assembly 79 and is operated to permit fluid flow in the one direction from line 76 to conduit 78 and prevent fluid flow in a reverse direction. Thus, fluid under pressure supplied by the pump and motor to the control valve assembly 79 cannot be bled oil from valve assembly 79 through the pump 66 after the pump has stopped operating. The solenoid valve 72 has an inlet line or conduit 81 coupled to the conduit 78 between the check valve and control valve assembly and an outlet 82 to the reservoir 61. The solenoid valve 72 is normally closed and, when actuated by solenoid 74, serves to bleed off fluid pressure from the control valve assembly 79. From the foregoing, it will be appreciated that the power section permits fluid from the reservoir to be supplied to the control valve assembly 79 and provides for selective coupling of the control valve assembly to the reservoir.

The control valve assembly 79 includes a piston 33 slidably mounted within a cylinder 84. A shoulder 86 in the cylinder restricts the size of the lower portion of the cylinder to limit the downward movement of the piston therein. A spring 87 is positioned between one side of the piston and the lower end of the cylinder 84. An inlet port 88 connects the cylinder 84 with the conduit 78 providing fluid from the pump 66. An outlet port 89 is also provided in the wall of the cylinder and is connected by means of a flexible conduit 91 to an inlet port 92 on the lower end of the actuating cylinder 48 below the piston 46. A third port 93 in the lower end of the control valve cylinder 84 provides for fluid communication between the reservoir 61 and the lower end of the cylinder 84.

The power or actuating means which is carried by the support link member 20 is also shown in FIGS. 4 and 5. This power means consists of the cylinder 48 in which the actuating piston 46 is slidably mounted, the piston rod 44 being connected to piston 46. Movement of the piston 46 in an upward direction within the cylinder 48 compresses a main actuator spring 94 positioned in the upper end of the cylinder between the piston 46 and the upper end of the cylinder. A port 96 in the upper end of the cylinder is connected to a flexible conduit 97 which provides fluid communication between the hydraulic reservoir 61 in the tool housing and the power actuating cylinder 48 above the piston 46. A third port 98 in the cylinder wall is connected by means of a conduit 99 with the port 92. A bypass valve 101 is provided in conduit 99 for filling the cylinder above and below piston 46 with oil when the tool is serviced.

Referring now to FIG. 7, the power actuating piston 46 forms an assembly which includes a cylindrical portion 102 rising from the upper side of piston 46, which portion 102 is threaded at its upper end to receive a plug member 103 having a central recess 104 therein. Ports 100 in the cylindrical portion 102 and port 105 in the plug member 103 permit passage of fluid from the upper portion of cylinder 48 into the cylinder portion 102 and recess 104 at reservoir pressure. A constant pressure compensating piston 106 is slidably received within the cylinder portion 102 of the piston assembly and a rod 107 extending upwardly from the piston 106 has its upper end received in the recessed portion 104 of the plug. A resilient means such as Belleville washers 109 are positioned between the plug 103 and the piston 106. One or more passageways 111 are formed through the actuating piston 46 to provide fluid communication between the power actuating cylinder 48 below the piston 46 and the interior of the cylinder portion 102 below the piston 106. A caliper potentiometer 112 (FIG. 4) is mounted in the upper end of the actuating cylinder 48. A follower shaft 113 extending downwardly from the potentiometer 112 rides on the upper end of the plug portion 103 of the piston assembly. A spring 114 is mounted about the potentiometer follower shaft 113 and bears against a flange on the shaft to urge the shaft to an extended position and into contact with the top surface of the piston assembly plug 103. An adjustment screw (not shown) may be installed in the top end of the potentiometer housing to permit adjustment of the potentiometer.

Electrical circuits and wires for operating the motor and solenoid valve and for transmitting signals from the potentiometer and well logging device to the surface have been omitted from the drawings and description in that such circuits are conventional and well known in the art.

Turning now to the operation of the above-described apparatus, in accordance with the present invention, the linkage system to develop relative movement between the shoe 22 and skid housing 19 will be discussed first, and thereafter the hydraulic system will be explained. In the linkage system, when the piston 46 is in the lower portion of cylinder 48, the shoe 22 and skid housing 19 are extended relative to one another and are in the logging position. This mode of operation is shown in FIGS. 1

and 4. Conversely, when the actuating piston is in an uppermost position within the cylinder 48, the shoe and skid housing are retracted relative to one another for ascending or decending to the zone in the borehole to be logged as shown in FIGS. 2 and 5. The uppermost and lowermost positions of the actuating piston within the cylinder 48 represent the extreme relative positions of the shoe and skid housing. Hence, it will be appreciated that for an average diameter of a borehole, the piston will be in an intermediate position in cylinder 48. As shown in FIGS. 1 and 4, when the actuator piston in cylinder 43 moves under the force of spring 94 toward its lowermost position, the rod 44 pushes on link member 38. This movement of the rod is transmitted through link 38 to the short end 24a of arm 24. Upon downward movement of the short portion 24a of the eccentering arm, the arm pivots about pivot point 36 to move the outermost end of the long portion 24b of the arm 24 outwardly into contact with the wall of the well bore.

As shown in FIGS. 2 and 5, when the actuating piston in cylinder 48 is moved under fluid pressure toward its uppermost position, the rod 44 acting through the link 38 pulls up on the short end 24a of the eccentering arm vto pivot the long end of the arm 24b about pivot point 35 and move the outermost end of the arm downwardly and inwardly so that the shoe 22 is positioned within the protective confines of chassis 14. The apparatus in this condition may be lowered into the well bore to the level where commencement of the logging operation is desired.

It should be noted particularly that moments or forces due to the extension and retraction of arm 24 and skid housing 19 are not imparted to chassis 14. This is because the movement of the actuating rod 44 and reaction forces caused by such movement are substantially in a single plane of operation so that the main moments and forces cancel out, leaving a relatively negligible force imposed upon chassis 14. This single plane of operation is defined by pivot points 50, 45, 40 and 34 in the linkage system which points lie approximately in a straight line. Therefore no moment forces are developed about the pivot 50 and; the forces are substantially equal and opposite. Housing 19 is free to pivot about pivot point 34 and the supporting link member 20, which carries the actuating piston and cylinder, is free to pivot about the pivot point 50. This permits the housing 19 to follow the inclinations of the wall of the borehole free and independent of forces or positioning of the chassis 14 in the well bore and the chassis 14 is free to follow the inclination of the borehole free and independently of the housing 19.

The operation of the hydraulic system can best be understood by references to FIGS. 4 and 5 of the drawings.

FIG. 5 shows the actuating piston 46 in its uppermost position in cylinder 48 which retracts the arm 24 and housing 19. An electrical power circuit (not shown) is energized at the surface to provide power to operate the motor 68. The motor 68 drives the pump 66 which pumps oil from the reservoir 61 through conduits 76 and 78 and check valve 71 to the inlet port 88 of the control valve assembly 79 moving the control valve piston 83 from its position shown in FIG. 4 to the position shown in FIG. 5. Movement of the control valve piston '83 downwardly in cylinder 84 opens the outlet port 89 in the cylinder to permit the oil being pumped through conduit 78 to flow through the conduit 91 into the lower end of the actuating cylinder 48 through port 92. This oil under the pressure of the pump 66 acts on the bottom side of the actuating piston 46 to move the piston to its uppermost position in the cylinder against the force of the actuating cylinder spring 94. Once the piston 46 moves to its uppermost position thereby retracting the wall-engaging members, i.e., arm 24 and housing 19, against the protective housing of the tool, the pumping of hydraulic fluid is stopped. When the tool is closed, the relief valve '70 opens at a predetermined pressure to prevent pressure in the system from becoming too high before the pumping of the fluid is stopped. The position of the wall-engaging members is monitored at the surface by observing a galvanometer or the like which is fed by a signal from the caliper potentiometer 112.

The check valve 71 in the fluid supply conduit traps the hydraulic fluid to maintain the pressure on the conduit 78 and on the control valve piston 83 and thereby hold the actuating piston 46 in its uppermost position in the cylinder 48. This trapped volume of oil between the check valve 71 and the actuating piston 46 in cylinder 48 is not pressure balanced. However, the passageways 111 in piston 46 (FIG. 7) open this trapped fluid to the underside of piston 106. The Belleville springs 109 acting against piston 106 keep the pressure in this closed portion of the hydraulic system at tolerable values thereby serving as a volume compensating device under varying temperature and pressure conditions.

With the actuating piston 46 in this uppermost position and with the wall-engaging members retracted, the tool is in the proper position for lowering into a well bore. Upon reaching the desired depth in which the logging operation is to be commenced, the solenoid valve 72 which is operated by an electrical circuit (not shown) is actuated to open a fluid communication path between the conduit 78 and the reservoir 61. This opening of the solenoid valve 72 relieves the pressure on the control valve piston 83 and permits an upward movement of the control valve piston under the force of spring 87. This upward movement of piston 83 closes the inlet port 88 to the control valve and opens the outlet port 89 to fluid communication with the reservoir through port 93 in the lower end of the control valve. With the control valve piston in this position (FIG. 4), the portions of the actuating cylinder 48 above and below the actuating piston 46 are both in communication with the reservoir 61 thus permitting the actuating spring 94 to move the actuating rod 44 downwardly until the wall-engaging members of the tool have extended into contact with the well bore. When extending the wall-engaging members for logging, the solenoid operated valve should be continuously energized to the open position until the wall-engaging members both come up against the formation. This can be determined by monitoring signals from the caliper potentiometer. When the wall-engaging members are fully extended and actuating piston 46 has ceased moving downwardly, the pressure in conduit 91 decreases to a level to permit the control valve piston 83 to shift to the logging position (FIG. 4) in cylinder 84 and release the arm 24 for free movement against the force of spring 94.

Subsequent movement of the tool in the well bore and movement of the wall-engaging members in relation to changes in contour of the welll bore will move the actuating piston 46 against the face of the actuating spring 94. For the average diameter borehole, the actuating piston 46 will be in an intermediate position in the cylinder 48. Should the well bore diameter decrease, the actuating piston will be moved upwardly to further compress the spring 94; while if the well bore diameter increases the actuating piston will be moved downwardly under the influence of the spring 94. The spring 94 has a spring constant defining a linear relationship between force and deflection or length force function. The relative angular and positional disposition of pivots 45, 40, 34 and 36, and the eccentering arm 24 compensate for the linearity of the length-force spring function so that a relatively uniform force is applied to hold the shoe 22 and the skid housing 19 against the walls of the well bore over the range of the well bore diameters in which the tool is intended to opcrate.

The diameter of the well bore is measured by the potentiometer 112 which measures the travel of the actuating piston 46 in cylinder 48, the travel of the actuating piston being proportional to the relative spacing between the shoe 22 and skid housing 19.

To summarize the above-described operation, the sequence of the operating steps will be described:

TO INSERT THE TOOL IN THE WELL BORE (l) The pump and motor are operated to actuate the control valve 79;

(a) the control valve 79 operates to provide fluid under pressure to the lower end of cylinder 48 while the upper end of cylinder 4% is constantly open to reservoir 61 thereby permitting movement of the actuating piston upwardly in cylinder 48;

(b) movement of the actuating piston upwardly, through rod 44, link 38, short arm 24a, and brace 35, retracts arm 24 and skid housing 19 into the confines of chassis 14;

TO LOG IN WELL BORE (1) The normally closed solenoid valve 72 is held open to release the holding pressure on the control valve thereby permitting the control valve piston 83 to move upwardly when the wall-engaging members are in c0ntact with the well bore.

(a) the control valve piston 83 in such position, couples the lower end of the actuating cylinder 48 to the reservoir permitting the actuating piston to be responsive to the force of the main actuating spring 94 to urge the actuating piston 46 downwardly in relation to cylinder 48;

(b) movement of the actuating piston downwardly through rod 44, link 38, short arm 24a and brace 35, extends the arm 24 and skid housing 19 into contact with the walls of the well bore.

(2) The tool assembly is raised to log the well bore with the arm 24 and skid housing 19 moving inwardly and and outwardly relative to one another at sections of the well bore having different diameters. The relative inward movement compresses the main actuator spring 94 whereas relative outward movement is accomplished by the force of the main spring 94 acting against the actuating piston 46. Movement of the actuating piston in cylinder 48 is detected by the potentiometer follower shaft 113 to provide surface indications of the diameter of the well bore. The logging tool, having, for example, a source and detector of radioactivity in skid housing 19, is held in close proximate contact with the sidewall of the well bore. The skid housing 19 is freely supported on the link member so as to follow changes in the contour of the well bore and be held in proximate contact with the well bore by arm 24 and shoe 22; and the housing 12 and chassis 14 are free to move independently to follow the borehole.

(3) After the traversing of the section of well bore which is being logged, the pump and motor are operated and the arm 24- and skid housing 19 are again retracted, as described above, and the tool assembly is retrieved from the well bore.

It will also be appreciated from the foregoing that other tools may be employed within the main housing as, for example, an electrical surveying device, a sonic measuring device, a radioactive logging device, etc. These other tools may be selectively arranged in the upper end of the main housing assembly 12 to operate in conjunction with the tool such as a a-ot logging tool in the skid housing to provide combination measurements of the various parameters of the earth formations. It will also be apparent that the shoe or pad 22 may carry electrodes or the like for detecting other properties of the formation, thereby further increasing the versatility of the apparatus.

Likewise one or more other logging devices may be mounted in tandem with the device heretofore described. Such an arrangement is shown in FIG. 8 wherein the above-described logging apparatus 18 is carried by skid housing 19 and connecting link 20 from pivot point 50. In conjunction therewith FIG. 8 shows a second logging apparatus 21 mounted on a skid housing 19a and connected to a supporting link 2021. A chassis extension 14a is threadedly attached at 17 to chassis 14 to provide a protective housing for the apparatus 21. The connecting link member 2011 is pivotally attached to the chassis 14a at pivot point 50a. The hydraulic system including motor, pump and reservoir is provided in the main housing 12 and furnishes hydraulic power to the actuating mechanisms on both connecting links 20' and 20a.

In the tandem tool set-up described above, the hydraulic fluid must travel a greater distance from the lower tool to the reservoir than in the upper tool. For this reason it is desirable to place the control valve assembly 7 near the actuating mechanism. Such an arrangement is illustrated in FIG. 9 where the control valve assembly is shown positioned on the upper end of the actuator housing. This permits fluid, during the logging phase of operation, to pass from one side of the actuating piston 46 to the other through a minimum length of hydraulic line thus providing a more sensitive response of the actuator to changes in the well bore configuration. Additionally, quick disconnect couplings are used to connect hydraulic lines between the housing and actuator mechanism. These couplings have a restriction therein which reduces the amount of fluid flow through the disconnect coupling, thus providing a further reason for locating the control valve on the actuating mechanism. However, it should be pointed out that the control valve can be located anywhere in the hydraulic system between the check valve 71 and the actuating cylinder.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and therefore the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. Apparatus for use in a well bore comprising: a first housing adapted for passage through a well bore; a depending, second housing adapted for engagement with a well bore wall; a piston cylinder pivotally interconnecting said first and second housings and comprising the sole connection therebetween to permit said second housing to move laterally relative to said first housing; an arm member pivotally connected to said second housing for movement between retracted and extended positions relative to said second housing; and piston means slidably received by said piston cylinder and adapted for moving said arm member to its said extended position to place said arm member into engagement with a well bore wall to provide a reaction force to urge said second housing into engagement with the opposite wall of a Well bore and for returning said arm member to its said retracted position.

2. Apparatus for use in a Well bore comprising: a first housing adapted for passage through a well bore; a depending, second housing adapted for engagement with a well bore Wall; a link member pivotally connected at its ends to said first and second housings to permit said second housing to pivot relative to the link member independent of said first housing; actuating means carried by said link member; an arm member having one end arranged to be movable between a normally retracted position adjacent said second housing and an extended position relative to said second housing, said arm member being pivotally connected intermediate its ends to said second housing; and a linkage coupled between said actuating means and the other end of said arm member, said actuating means being arranged to displace said arm member from its said retracted position toward its said extended position and into engagement with one wall of a Well bore thereby providing a reaction force to urge said second housing into engagement with the opposite wall of a Well bore.

3. Well apparatus comprising a housing arranged to be suspended for movement through a well bore and having a single pivotal connection thereon; a first wall-engaging member; a second Wall-engaging member; a piston cylinder pivotally interconnecting said pivotal connection with said first wall-engaging member and comprising the sole connection therebetween to support said first wall-engaging member for tilting and lateral movement relative to said housing; an arm member pivotally connected intermediate its ends with said first wall-engaging member and connected at one of its ends to said second wall-engaging member; and a piston member slidably disposed in said cylinder and connected to the other end of said arm member for moving said wall-engaging members selectively.

4. The apparatus of claim 3 further including: hydraulic fluid supply means communicating with said piston cylinder and including a reservoir, a pump, and a selectively operable control valve connected directly to said piston cylinder for regulating the flow of hydraulic fluid from said reservoir and pump to said piston cylinder, said control valve having an operating element normally held in a first position by hydraulic pressure for trapping hydraulic fluid in said piston cylinder at a pressure greater than the pressure in said reservoir; and electrically operated means for venting hydraulic pressure from said control valve to permit said operating element to move to a second position placing said piston cylinder at reservoir pressure.

5. The apparatus of claim 3 further including: hydraulic fluid supply means including a reservoir, a pump, and a selectively operable control valve connected by a flow line directly to said piston cylinder for regulating the flow of hydraulic fluid from said reservoir and pump to said piston cylinder, said control valve having an operating element normally held in a first position by hydraulic pressure for trapping hydraulic fluid in said piston cylinder at a pressure greater than the pressure in said reservoir; check valve means positioned in a hydraulic line between said pump and said control valve for trapping hydraulic fluid under pressure between said check valve and said control valve to maintain said operating element in said first position when said pump is not operating; and electrically openated means for reducing the pressure of the hydraulic fluid between said check valve and said control valve to permit said operating element to move to a second position placing the fluid in said piston cylinder at reservoir pressure.

6. The apparatus of claim 3 further including: hydraulic fluid supply means including a reservoir, a pump, and valve means for regulating the flow of hydraulic fluid from said reservoir and pump to said piston cylinder, said valve means being arranged to trap hydraulic fluid in said piston cylinder at a pressure greater than the pressure in said reservoir; and pressure compensating means for limiting the pressure of said trapped hydraulic fluid in said piston cylinder.

7. A well apparatus for use in a well bore comprising: first and second elongated housings, a supporting link member having a pivotal connection with each of said housings, the pivotal connection between said first housing and said link member providing the sole supporting connection for said second housing to permit said housings to tilt and move later-ally relative to one another, said pivotal connection between said first housing and said link member including a I-slot and pin arranged to permit convenient detachment of said link member from said first housing, and means carried by said supporting link member between said first and second housing for urging said second housing into proximate contact with the wall of a well bore.

8. Well apparatus including an elongated main housing arranged to be suspended from its upper end for movement through a well and an assembly supported by said housing solely through a single pivotal connection therewith, said assembly comprising: an elongated first wallengaging member; a second wall-engaging member; a first link supported from said single pivotal connection and pivotally connected with said first wall-engaging member to support said first wall-engaging member for tilting and lateral movement relative to said housing; an arm member pivotally connected intermediate its ends with said first wall-engaging member and connected at one of its ends to said second wall-engaging member; power means carried by said first link, said power means including a piston movable within a cylinder, a spring for urging said piston in a first direction, and hydraulic fluid supply means for urging said piston in a second direction; and a piston rod connected between said piston and the other end of said arm member for moving said wall-engaging members to either of said positions.

9. A tool for use in a well bore where it is desired to place the surf-ace of one housing in parallel contact with the wall of the well bore comprising: a main housing, an

actuating housing pivotally coupled at one end to said main housing, a wall-contacting housing, said actuating housing at its other end being coupled to said wall-contacting housing, said actuating housing having a cylinder and a piston, a wall-engaging arm pivotally coupled to said wall-contacting housing, said piston having an attached rod pivotally coupled to one end of said arm so that movement of said piston either retracts or extends said arm relative to said wall-contacting housing, spring means in said cylinder acting on said piston to normally extend said arm relative to said wall-contacting housing,

said cylinder being enclosed relative to said piston and rod, a hydraulic system coupled to the ends of said cylinder and including means for applying fluid pressure to one side of said piston to move said arm and wall-contacting housing to a retracted position while the other side of said piston is at a lower pressure, and means for equalizing pressure across said piston whereby said spring can extend said arm and wall-contacting housing.

10. A tool for use in a well bore where it is desired to place the surface of one housing in parallel contact with the wall of the well bore comprising: a main housing, an actuating housing pivotally coupled at one end to said main housing, a wall-contacting housing, said actuating housing at its other end being coupled to said wall-contacting housing, said actuating housing having a cylinder and a piston, a wall-engaging arm pivotally coupled to said wall-contacting housing, said piston having an attached rod pivotally coupled to one end of said arm so that movement of said piston either retracts or extends said arm relative to said wall-contacting housing, spring means in said cylinder acting on said piston to normally extend said arm relative to said wall-contacting housing, said cylinder being enclosed relative to said piston and rod, a hydraulic system coupled to the ends of said cylinder and including means for applying fluid pressure to one side of said piston to move said arm and wal1-contacting housing to a retracted position while the other side of said piston is at a lower pressure, means for equalizing pressure across said piston whereby said spring can extend said arm and wall-contacting housing, hydraulic fluid reservoir and pump means carried by said main housing for supplying said fluid under pressure to said hydraulic system, and selectively operable solenoid valve means for controlling said pressure equalizing means.

11. A tool for use in a well bore where it is desired to place the surface of one housing in parallel contact with the wall of the well bore comprising: a main housing; an actuating housing pivotally coupled at one end to said main housing; a wall'contacting housing, said actuating housing at its other end being coupled to said wallcontacting housing, said actuating housing having a cylinder and a piston; a wall-engaging arm pivotally coupled to said wall-contacting housing, said piston having an attached rod pivotally coupled to one end of said arm so that movement of said piston either retracts or extends said arm relative to said wall-contacting housing; spring means in said cylinder acting on said piston to normally extend said arm relative to said contacting housing, said cylinder being enclosed relative to said piston and rod; a hydraulic system coupled to the ends of said cylinder and including means for applying fluid pressure to one side of said piston to move said arm and wall-contacting housing to a retracted position while the other side of said piston is at a lower pressure; means for equalizing pressure across said piston whereby said spring can extend said arm and wall-contacting housing; and volume compensation means for limiting the pressure in said fluid pressure applying means, said volume compensation means including a chamber formed in said piston, 21 valve member slidable in said chamber, resilient means positioned between one end of said chamber and said valve member, and passage means connecting the other end of said chamber with said cylinder.

12,. An apparatus for use in a well bore comprising: first and second elongated housings, a supporting link member having a pivotal connection with each of said housings, power means carried by said supporting link member for urging said second housing into proximate contact with the wall of a well bore, said power means including a hydraulic piston and cylinder, hydraulic fluid supply means communicating with said cylinder and including a selectively operable control valve for regulating the flow of hydraulic fluid to said cylinder, said control valve also being carried by said supporting link member and having an operating element normally held in a first position by hydraulic pressure, and electrically operated means for venting hydraulic pressure from said control valve to permit said operating element to move to a second position.

13. An apparatus for use in a Well bore comprising: an elongated housing and a wall-engaging member connected to said housing, said wall-engaging member being arranged for lateral movement relative to said housing; power means connected to said wall-engaging member for moving said wall-engaging member laterally relative to said housing, said power means including a piston and cylinder; hydraulic fluid supply means including a reservoir, a pump, and valve means for regulating the flow of hydraulic fluid from said reservoir and pump to said cylinder, said valve means being arranged to trap hydraulic fluid in said cylinder at a pressure greater than the pressure in said reservoir; and pressure compensating means for limiting the pressure of hydraulic fluid in said cylinder, said pressure compensating means including a chamber, a compensating piston slidable in said chamber, and a resilient means positioned between one end of said chamber and said compensating piston.

14. An apparatus for use in a well bore comprising: an elongated housing and a wall-engaging member supported by said housing, said wall-engaging member being arranged for lateral movement relative to said housing; power means connected to said wall-engaging member for moving said wall-engaging member laterally relative to said housing, said power means including a piston and cylinder, said piston being slidably received in said cylinder and dividing said cylinder into first and second portions; hydraulic fluid supply means including a reservoir and a pump for supplying fluid under pressure to said first portion of said cylinder; and pressure compensating means in said piston for limiting the pressure of hydraulic fluid in said first portion of said cylinder, said pressure compensating means including a chamber with means for placing one end of said chamber in fluid communication with said first portion of said cylinder and means placing the other end of said chamber in fluid communication with said second portion of said cylinder, a compensating piston slidable in said chamber, and resilient means positioned between one end of said chamber and said compensating piston.

15. A tool for use in a well bore where it is desired to place the surface of a housing in parallel contact with the wall of the well bore comprising: a main housing, an actuating housing pivotally coupled at one end to said main housing at a first pivot point, a wall-contacting housing, said actuating housing at its other end being coupled to said wall-contacting housing at a second pivot point, said actuating housing having a cylinder and a piston, and a wall-engaging arm pivotally coupled to said wall-contacting housing, said piston having an attached rod pivotally coupled to one end of said arm at a third pivot point so that movement of said piston either retracts or extends said arm relative to said wall-contacting housing, said first, second and third pivot points lying in a substantially vertical plane.

16. A tool for use in a well bore where it is desired to place a pair of wall-contacting housings in contact with the wall of the well bore comprising: a main housing, a pair of piston cylinders positioned one above the other and each being pivotally coupled at one end to said main housing, a pair of wall-contacting housings, each of said piston cylinders at their other end being pivotally coupled to a respective one of said wall-contacting housings, piston members in each of said piston cylinders, and means respectively connecting said piston members to a respective one of said wall-contacting housings for selectively moving said wall-contacting housings laterally relative to said main housing.

17. The apparatus of claim 16 further including: bydraulic fluid supply means on said main housing for selectively moving said piston members within their respective piston cylinder.

18. A tool for use in a well bore where it is desired to place the surface of a housing in contact with the wall of the well bore comprising: a main housing, an actuating housing pivotally coupled at one end to said main housing, a wall-contacting housing, said actuating housing at its other end being coupled to said wall-contacting housing, said actuating housing having a cylinder and a piston operably connected to said wall-contacting housing for moving said wall-contacting housing laterally relative to said main housing, said cylinder being enclosed relative to said piston, a hydraulic system coupled to the ends of said cylinder and including means for applying fluid pressure to one side of said piston to move said wall-contacting housing, and control valve means on said actuating housing for selectively equalizing the pressure on each side of said piston.

19. A well tool for use in a well bore comprising: a main housing, a pair of wall-contacting housings positioned one above the other, a pair of supporting link members each being pivotally connected between said main housing and respective wall-contacting housings, actuator means carried by each of said supporting link members for urging said wall-contacting housings into proximate contact with the wall of a well bore, said actuator means each including a hydraulic piston and cylinder, hydraulic fluid supply means communicating with each of said cylinders and including a reservoir, and a selectively operable control valve on each of said actuator means for regulating the flow of hydraulic fluid to said cylinder, said control valves each having an operating element normally held in a first position by hydraulic pressure for maintaining hydraulic fluid against said cylinder under a pressure greater than the pressure in said reservoir, said operating element being selectively movable to a second position placing each side of said cylinder at reservoir pressure.

References Cited UNITED STATES PATENTS 2,766,533 10/1956 Brandon 33178 2,854,758 10/1958 Owen 33-178 3,023,508 3/ 1962 Saurenman 33-178 3,175,392 3/1965 Tharalson et al. 73-152 X 3,232,115 2/1966 Bennett et al. 73-152 X 3,254,221 5/1966 Saurenman 25083.6

CHARLES E. OCONNELL, Primary Examiner.

DAVID H. BROWN, Examiner. 

1. APPARATUS FOR USE IN A WELL BORE COMPRISING: A FIRST HOUSING ADAPTED FOR PASSAGE THROUGH A WELL BORE; A DEPENDING, SECOND HOUSING ADAPTED FOR ENGAGEMENT WITH A WELL BORE WALL; A PISTON CYLINDER PIVOTALLY INTERCONNECTING SAID FIRST AND SECOND HOUSINGS AND COMPRISING THE SOLE CONNECTION THEREBETWEEN TO PERMIT SAID SECOND HOUSING TO MOVE LATERALLY RELATIVE TO SAID FIRST HOUSING; AN ARM MEMBER PIVOTALLY CONNECTED TO SAID SECOND HOUSING FOR MOVEMENT BETWEEN RETRACTED AND EXTENDED POSITIONS RELATIVE TO SAID SECOND HOUSING; AND PISTON MEANS SLIDABLY RECEIVED BY SAID PISTON CYLINDER AND ADAPTED FOR MOVING SAID ARM MEMBER TO ITS SAID EXTENDED POSITION TO PLACE SAID ARM MEMBER INTO ENGAGEMENT WITH A WELL BORE WALL TO PROVIDE A REACTION FORCE TO URGE SAID SECOND HOUSING INTO ENGAGEMENT WITH THE OPPOSITE WALL OF A WELL BORE 